All,
To conclude the drama, after getting the key back from the UK and easily registering the key with the immoboliser and NOT successfully being able to program the doors, (most likely due to different frequency), I took it to lexus again and they tried to clone it again and it didn't work again.
So in conclusion, the key from UK won't work with the door as they must use a different frequency.. (WTF) but can be programmed with the immobiliser. So it can be used, however it will never be another master key!. So if you lose your original key, this spare will be able to open the doors, (manually) start the car etc, however you won't be able to ever program another master key.
All in all, unfortunately it wasn't worth getting the key (as I paid a premium thinking I was getting the whole master key). Otherwise, you can purchase a second hand lexus key (from australia) from someone, then buy a new blade and case off ebay for cheaply and then program it.